Wolverines shown to be driven to roam

Carnivores known for strength, ferocity, tales surrounding them

April 17, 2005|By NEW YORK TIMES NEWS SERVICE

GLACIER NATIONAL PARK, Mont. - In the gathering darkness, four biologists wearing headlamps surround an unconscious wolverine that is flat on its back. They check a transmitter implanted in its belly and fit another, larger one on a collar around its heavily muscled neck.

Then they inject the animal with the antidote to the drug that knocked it out and place it in a box trap. An hour or so later, when the lid of the trap is opened, the animal clambers out and runs into the forest.

Every two hours the position of the wolverine - known as M-1 - is fixed by a geo-positioning satellite and recorded in the collar. A few weeks later, the wolverine is recaptured, and a record of its travels is downloaded from the collar into a laptop. The result confirms data that the researchers have accumulated over three years: Wolverines are peripatetic.

"The hallmark of the wolverine is its insatiable need to keep moving," said Jeff Copeland, director of the research project and a wildlife biologist at the Rocky Mountain Research Station of the U.S. Forest Service in Missoula, Mont. "I don't know any animal that moves like this every day - nothing close."

The wolverine, a creature of the northern forests that resembles a small bear, is legendary for its strength and ferocity.

"Picture a weasel," Ernest Seton Thompson, the naturalist, wrote in 1909, " ... picture that scrap of demoniac fury, multiply that mite some 50 times, and you have the likeness of a wolverine."

An Austrian biologist named Peter Krott - who raised wolverines and wrote about them in his 1959 book, Demon of the North - said one of his animals, named Rosa, got caught in a leg-hold trap and traveled back home on three legs for weeks, carrying the steel trap in her jaws, before collapsing on his doorstep.

John Krebs, a biologist in British Columbia who studied wolverines for seven years and is writing up his research, said that in the 1930s, a wolverine kept chewing into a log meat locker at a mountain lodge and dragging slabs of meat out. Leg-hold traps were set. One day the trapper surprised the wolverine at work. With traps on three legs, it was still trying to drag a carcass.

The tales that have accumulated about the animals would have it that one wolverine can pull a moose carcass on its own. Krebs documented a 35-pound wolverine dragging a mountain goat several kilometers and across a major highway.

"Determined," Krebs said. "That describes them best."

The new research shows a wolverine that seems driven to roam. It keeps on moving at about five miles per hour, whether the terrain is rough or easy. With broad feet that serve as natural snowshoes, it easily scrambles over 10,000-foot snow-covered mountains, crosses giant scree piles and lopes through lichen-draped forests, sometimes covering 25 miles one day and 25 miles back the next. A male's home range is about 500 square miles, about the same as that of a grizzly bear, which is 10 times its size.

A male covers that huge swath of territory to mate with three or four females, rummage in avalanche chutes for the carcasses of moose or mountain goats, hunt squirrels and insects, or scrounge for berries. "The things it needs to make a living are scattered, so they need that big an area to find what they need," Copeland said.

The wildlife biologist Rick Yates, who works on the study, said, "Everyone who studies the animal comes away impressed by it."

Wolverines are similar to the Tasmanian devil (but not related to it) and are said to be fearless. "A wolverine can probably hold its own against any other carnivore," Copeland said. But it seldom fights because "it can probably bluff its way out of any confrontation."

Before it was freed from the trap in Glacier, M-1 growled and woofed as researchers neared the box. When Copeland, who has never been bitten, cracked the lid, the animal lunged forward, snarling, and ripped out pieces of the log with its teeth.

Wolverines are also proving to have a family life unusual for carnivores. Males have been known to wait outside a trap for a captured mate.

In Idaho in the 1990s, Copeland said, he kept catching a young female wolverine called 203. She couldn't survive on her own and was living on the bait in the trap. The next day, Copeland's wildlife technician called from an aircraft and said, "You're not going to believe this, but little 203 is with Socks."

Socks, with four white feet, was the patriarch wolverine of the area and probably was 203's father. She would spend two or three days with Socks; they would split, then come back together for another two or three days. "I think he was teaching her to survive," Copeland said. "It suggests male parental care, which in carnivores is unheard of. But it enhances the kit survival and assures likelihood of passing on his genes."

No other young adult carnivores are known to maintain companionship with their doting fathers.

Wolverines, the largest member of the weasel family, inhabit tundra and high-mountain habitat around the globe. They are found throughout Alaska and much of northern Canada, but in the contiguous United States, their range extends only into the northern Rockies in Montana, Idaho and Wyoming. A few have also been sighted in northern Washington state. Because the animals are so reclusive, population numbers are difficult to estimate, but Copeland said the population in the lower 48 states is "in the hundreds, not the thousands."

Until the 1930s, they were found as far south as the Sierra Nevada in California and in Colorado. "Wholesale poisoning probably whacked them," Copeland said. There are none in Michigan, the Wolverine State, he added.